1. Field of the Invention
The present invention is directed generally to a housing for an electromechanical component having a tightly closed hollow interior and an outwardly open or openable aeration opening, and in particular to a plastic housing for an electromagnetic relay or similar switching equipment.
2. Description of the Related Art
Relays which have plastic housings are usually sealed with an adhesive, a casting resin, or the like so that the sensitive parts within the housing, and in particular the contacts, are protected against the harmful influences of washing solutions, soldering agents and the like.
Under certain circumstances, however, the tightly closed housing can be disadvantageous for the further useful life of the relay or similar component since the plastic housing, the coil and other parts in the relay emit various vapors, gases and the like over the course of time that are harmful to the contacts and that generate a microclimate within the closed housing. Such emissions may be more harmful to the contacts than normal ambient air. It is therefore often standard practice to provide an aeration opening in the housing that can be opened only after the integration of a relay into the housing. Thus, for example, it is known to puncture a prepared, thin walled section of a relay wall, as disclosed in German Published Application 30 39 702, or to cut off a cylindrical or rectangular bleb at a housing corner as disclosed in German Patent Document 87 03 079. However, the possibility of initially covering a passage formed in the housing with a foil and then of pulling the foil off after the relay has been washed and soldered is also possible.
There is the risk with such aeration openings that metal parts arranged inside the housing in the area of the aeration opening do not have adequately long insulating paths from other voltage carrying parts outside of the housing. This can occur, for example, when a relay is integrated on a first printed circuit board and an aeration opening on an upper side of the relay lies in the immediate proximity of an interconnect or a voltage carrying terminal member of a second adjacent printed circuit board. Difficulties particularly derive when mains relays are involved wherein long creep and air paths, for example of at least 8 mm, are required and prescribed for protection against electrical shocks.